The type of paper carton used particularly for domestic milk supply is well known. The form of carton is marketed under the Registered Trade Marks "ELOPAK", or "TETRA PAK". Such cartons are sealed by inclining the upper portions of the side walls inward with two opposite faces folded together to form so called "wings", and heat treating or otherwise sealing the mating internal extremities of the inclined portions to form a ridge. This ridge may be folded flat on the upper face of the carton, or it may be left in an upstanding attitude so that the upper face of the carton appears "gabled". The flat top types of cartons generally have tongues at each end of the folded ridge which are detachably secured to the side walls of the carton to keep the ridge in a flat folded position for transportation and sales display. Printed on such cartons are opening instructions, sometimes with illustrations.
However, many people find the opening instructions difficult to follow. People who are not particularly dextrous find their failure to open the cartons very frustrating. The failed attempts to open the cartons as instructed, can cause the wings to be tom, badly buckled or otherwise mutilated. This is hygienically undesirable and may cause the milk or other liquid in the carton to pour badly or dribble down the outside of the carton.